The disclosure generally relates to wide-band multimode optical fibers and, more particularly, to wide-band multimode optical fibers (MMFs) with cores having a radially-dependent alpha profile.
Optical fibers, including multimode optical fibers, are being envisioned for use in data centers and fiber home networks, among other applications, with enlarged operating windows to facilitate data transmission over increasingly larger wavelength ranges. For example, multimode optical fiber (MMF) designs with graded index cores are being designed and envisioned to operate over a range of wavelengths near 850 nm. Recent applications envision operating wavelengths that are not limited to wavelengths near 850 nm. Some recent applications envision operating wavelengths that are in a range of 840 nm to 860 nm. Additional recent applications envision operating wavelengths that fall within the range of 840 nm to 953 nm. Some of these new optical fiber designs are being contemplated with complex refractive index profiles, often with two or more dopants having different concentration profiles. In order to meet the OM4 standard for modal bandwidth set forth by TIA, the MMF must have an effective modal bandwidth (EMB) of 4700 MHz-km at 850 nm. Recently, a new standard for MMFs has been proposed and standardized by TIA, which is referred to as OM5 and documented in TIA-492AAAE. For an MMF to meet the OM5 standard the MMF must meet the OM4 EMB requirement at 850 nm while additionally providing an EMB at 953 nm of 2470 MHz-km.
The MMFs currently in production have peak wavelengths that are located near an upper end of a range that is acceptable for meeting OM5 standards set forth by TIA. The range that a peak wavelength can fall within to meet the OM4 standards set forth by TIA is roughly between 815 nm to 895 nm. In order to meet the OM5 EMB at 953 nm, current MMFs typically are provided with a peak wavelength at or above 880 nm. However, currently available MMFs that meet the OM4 standards typically have a differential modal dispersion (DMD) centroid at their peak wavelength that is flat, while the DMD centroid at longer wavelengths (e.g. 950 nm) typically shifts to a fronting or right-tilt profile, which can make it difficult to manufacture MMFs that meet the OM5 standard at 850 nm and 953 nm.
Accordingly, there is a need for wide-band MMFs with DMD centroids at their peak wavelength that have profiles that are tailing or left-tilted and have increased EMBs at wavelengths that are greater than 850 nm, for example, 950 nm.